Filter unit for air cleaners



Feb. 26, 1952 1 B 'SEBQK ETAL 21,587,234

FILTER UNIT FOR AR CLEANERS fzzezZUfE :7L-7557715.23. gebak fz//zzzzzz EEIUWZZE 12D/ E Fay/15h Feb. 26, 1952 Y .l. B. s`EBOK ETAL FILTER UNIT FOR AIR CLEANERS 2 SHEETS-SHEET 2 Filed July 5, 1945 jy Z9 Ewa/a i FHF/LQ? EZLQE.

Patented Feb. 26, 1952 UNITED STATES PATENT --oFFIcE v- 2,587,234 FILTET; UNI'LFOR AIRpLEANERs Joseph B. Sebok, Detroit, Mich., 'and William H. Browne and Arnold E. Pavlish, Columbus, Ohio, assignors to Houdaille-Hershey Corporation, Detroit, Mich., a corporation of' Michigan Application July 5, 1945, serial NQ. 603,304 'Y This invention relates to improvements in a filter unit for air cleaners, the filter unit being highly desirable for use in air cleaners associated with internal combustion engines, air compressors, brake mechanisms, and other equipment requiring a supply of clean air; and more particularly the invention is highly desirable for use in connection with automotive air cleaners of the type used with the internal combustion engine of a vehicle, although the invention may have other uses and purposes as will be apparent` to one skilled in the art.

It is an important object of the instant invention to provide a durable and economical filter unit for liquid bath air cleaners, which unit has a low bulk weight, high cleansing efliciency, practically eliminates the danger of carry-over of liquid through the cleaner outlet, has a more than satisfactorily low restrictiontothe flow of -air therethrough, and a relatively high capacity.

It is also an important feature of this invention to provide a filter element vor unit comprising a mass of 'fibrous strands, which unit .is'so constructed that high uniform density may be easily reproduced from filter tov filter in rapid and economical commercial manufacture, vwith only a negligible variance lbetween resultant filter units.

Still a further object of the instant invention is the provision of a fiber filter unit capable of unit for a liquid bath air cleaner, which unit ema'- filter unit for a liquid bath air cleaner so constructed as to embody the advantages of both '-aj filter unit with strands paralleling the air "stream and a filter unit with strands transverse to the air stream.

Also an object ofthe invention is the provision of a filter unit for liquid bath air cleaners, which unit is made up of a mass of vegetable fibers so arranged as to have some fiber portions paralleling the air stream, some fiber portions being disposed transverse to the air stream, and other 'fiber portions being disposed obliquely to the air stream. Also an object of the instant invention 1s une provision of an economical and durable filter bodies all'of the .required properties of a lter unit and whi'chmay be so economically manufactured as to warrant the discarding of a dirty unit and the substitution of a new unit therefor.` The filter unit embodied in the instant inwithstanding excessive vibration throughout a long life with no resultant adverse .coinpacting'v or channeling of the filter unit.

Also an object of this invention is the production of a highly eii'icient filter unit for vliquid bath air cleaners, said unit possessingall desirable properties, and comprising in the mainA a mass of curled vegetable bers bonded `together. A filter unit made up of strands generallyparalleling the flow of air through the unit provides a higher carry-over point for cleansing liquid by virtue of the unopposed surface attraction of the strands for liquid carried by traveling air. The

self-cleaning action of the cleaner is also augmented by strands generally paralleling the air path due to the increased circulation of cleansing liquid through the lower portion of the. lter unit. Limited advantages, which in most cases,

are more than oiset by the disadvantages, occur in a filter unit having the strands substantially transverse to the air stream. In such case,

droplets of fluid carried byv traveling air are quicker broken up by virture of the direct right vangle contact with a strand, and this is-especially true in connection with the breakingup of air bubbles dispersed throughout the fluid medium, which bubbles may be carrying injurious dirt therein.

With these thoughts in mind, it is an important object of the instant invention to provide vention costs so 'little that it would be just as economical, if not more so, to replace a dirty unit with anew one, rather than go to the time and labor necessary to cleanse the dirty unit.

While some of the more'salient features, characteristics and advantages of the instant invention have been above pointed out, others will become apparent from the following disclosures, taken in coniunction withr the accompanying drawings, in which:

Figure l1 is a central vertical sectional view,

'with parts in elevation, of an air cleaner and filter unit embodying yprinciples of the instant invention;

Figurez is a plan sectional view of the structure of Figure 1, taken substantially as indicated by the staggered section line II-II of Figure 1, look- -ing in the direction of the'arrows;

Figure 3 is a fragmentary and rather diagram- `matic view illustrating a bunch of fibers going to' make up the filter unit prior to the curling of the fibers;

Figure 4' is a fragmentary elevational view illustrating a step in the process of curling the fibers; A

Figure 5' is a' fragmentary view of a bunch of curled fibers indicating 'judicious points for cutting the fibers; and

ket holding formation 3 in which an annular gasket 4 may be seated. The upper margin of the lower section 2 is outwardly rolled as indicated at 5 to seat against the gasket when the casing sections are telescopically joined. The sections may be held in operative assembled relationship by one or more spring clamping arrangements including a lever 6 having a thumb engagingpontion "I, which lever is pivoted as indicated at 8 to a bracket 9 affixed to the casingv wall. A U- shaped spring element Ii), having a loop II in each leg thereof to increase its resiliency, is 'secured to the lever 6 above the pivot point 8. v-The lower end of the spring element or yoke of the U is turned upwardly as indicated at I2 to engage inside the groove dened by the rolled Inargin 5 on the lower casing section. The clamping arrangement is of the over-center type, and when the lever 6 is thrown upwardly to the position seen in Figure 1, the two casing sections are held together with the gasket 4 eiecting an air-tight seal therebetween.

The upper casing section is provided with a closed top I3 and in the side wall thereof there is a plurality of louver-like inlet openings I4 for dirty air. Inside this casing section `there is a housing or hood I5, preferably centrally disposed, and secured to the inside of the top I3. This housing or hood is of considerably less size than the casing section so as to leave an open space i6 therebetween to eiect a better distribution of incoming air. The hood or housing flares outwardly in its lower portion and .is joined to a filter holding shell I 'I provided with pressedout portions I 8 which may be spot welded to the casing wall to increase the rigidity of the entire structure.

As clearly seen in Figure 1, the lter .holding shell I1 is of less size than the adjacent casing wall so as to leave an annular passage I9 therebetween through which the incoming air descends from the chamber I 5 at the top of the cleaner.

Within the shell I1 is a lter unit generally indicated by numeral which may be removably held in position by means of a spring holder 2I seen better in Figure 2. This holding element 2| Vincludes. a pair of oppositely disposed legs having curvate end portions 22-22 which extend through suitable slots 23 in the wall of the shell I1. The central portion of the holding element is preferably U-shaped as indicated at 24 so that this centralY portion may be compressed between the thumb and nger of an operator to withdraw the curved portions 222-22 of the legs from the slots 23--23 and thus permit removal of the lter unit 20.

As will more fully appear later herein, air trav'- eling through the cleaner passes upwardly through the filter unit 20 into the open space thereabove within the hood or housing I5. An outlet conduit extends through both the casing wall and the wall of the housing I5 into the space above the lter unit, and the outer end of this conduit may be suitably attached to whatever mechanism is to be supplied with clean air. such for example as the carburetor intake of an internal combustion engine.

The lower casing section 2 mainly defines a sump for cleansing liquid such for vexample as crankcase oil. This section of the casing is shaped to define an outer annular trough-like portion 25 with an upwardly slopingvbridge 21 connecting the trough-like portion with a deeper central well 28. A splash ring is attached 1.11. am

4 suitable manner to the upper vportion of the wall of the central well and this splash ring has an inwardly and upwardly inclined flange 2d which is in effect a continuation of the wall 21. The

flange 29 prevents sump liquid from passing from the Well 28 into the trough 2t by virtue of jarring or Vbouncing of a vehicle or the like carrying the air cleaner.

`, In operation, incoming air enters the inlet openings I4, distributes itself substantially equally throughout the space l5, and descends the annular passage I5 toward the liquid sump. This incoming air initially drives out the liquid from the trough 26 and carries it upwardly into the lower 'portion of the lter element 20. The depth of the trough .26 metersY the amount of oil noi'- Amally in circulation through the lower portion `of the lter element during operation. As dirt laden liquid falls from the filter unit back into the sump, more liquid will be supplied to the trough 26 to be carried into the lter mass by the traveling air, so that the quantity in the H bales, or other types of packages, of a length in general from two to four feet. These raw sisal fibers frequently contain some portions of the leaves from which they were obtain-ed, or' other woody portions of the plant. It is therefore desirable to rst card the raw bers in any suitable carding mechanism so as to line up the bers in substantially parallel relationship and remove the undesirable woody material. The carded fibers are then preferably iireproofed or flameproofed, especially when the resultant filter unit is to be used in an rair cleaner for an internal combustion engine, where there may be backfire through the carburetor of the engine. The nreproofing may be accomplished either by immersion or by a spraying process, as may lbe deemedl most expedient. A satisfactory reproofing' substance is a twenty percent solution of ammonium.- sulfamate in water, and if immersion is the process employed, a period of time between five and ten minutes is satisfactory. After the appli,- cation of the reprooflng agent, the fibers are VIiiiifer'ably passed between pressure rollers so adjusted as to 'remove a major portion of the moisture from the bers.

vlThereafter, while the fibers are still damp from the 'application of the reproong material, they are Wrapped around a mandrel in the form of a single layer coil along the mandrel so as to impart a curl to the fibers. A mandrel of approximately one-eighth inch diameter may satisfactorily be used for this purpose. Then, while held in the curled position about the mandrel, the bers are dried, at a temperature approximating 250 F. for a period approximating one hour.. This drying operation not only dries out the moisture from the applied reproong material but the curl in the i'ibers is steamed into the .fibers by virtue of the water being driven off.

YFollowing this drying operation, the iibers may i?? 911.5 1PM? ,relatively short lengths, either while upon the mandrel or after 'removal 'from' the mandrel. By way of example, the fibers may be cut into lengths of approximately'one inch, which is a satisfactory length for-most filter units, and each length will thereby contain's'everal of lthe curls in the fiber. I s

With reference now to the drawings, especial- 1y Figures 3, 4 and 5, we have shown in Figure 3 a bunch of fibers generally indicated by numeral as they are before the curling operation. In Figure 4 we have diagrammatically shown a mandrel 3I with the bunchof fibers 30 curled tightly around the mandrel. As stated above, this curling operation is preferably done while the fibers are still damp from the application of the reproong material. In Figure 5 we have illustrated the bunch of fibers removed from the mandrel after the drying operation, and the dotted lines 32 and 33 indicate where the fibers may be cut into the short lengths. The showings in these figures of the drawings are exaggerated in comparison with the sizes given above, for the purpose of clarity.

Following the cutting operation, the short lengths of fiber Yare preferably separated one from the other, by a carding operation or the equivalent, and they may be spread out upon a substantially flat surface. A bonding medium is then sprayed or equivalently applied to the fiber lengths. Preferably, a plastic bonding medium is utilized, and this bonding medium may be either a thermoplastic or a thermo-setting plastic as may be deemed most desirable. By way of example, a thermoplastic resinous inaterial comprising acopolymer of vinyl chloride and vinylidenechloride may be dissolved in cyclohexan'one to the extent of seven parts per hundred of solution and then applied in a fine spray upon the carded or separated fiber lengths.

ySuch material has a relatively high melting 1 point, that is, a melting point above the temperature which can be satisfactorily employed in connection with sisal fiber. It is therefore necessary to pack the plasticized curled fiber lengths in a, mold before the applied plastic becomes dry. After the fibers are placed in a mold so that the resultant mass will have the desired shape of the filter element being manufactured, they are then subjected to a heat treatment to drive off the solvent from the plastic resinous material,

which heat treatment may vary from a period of time of vhalf an hour to two hours at la temperature between 200 to 300 F., depending upon the particular plastic bonding medium utilized.

There are several different ways in which the plastic treated and still wet fiber lengths may be shaped4 into the desired lter unit contour and thickness. One of these ways may consist in merely packing the fibers in a glass or metal mold of a size slightly in excess of that of the filter holding shell in the particular air cleaner for which the lter unit is to be made. The fibers are now packed into a compact mass akin to a piece of felt, but with just suilicient pressure to cause a bonding of one fiber to an adjacent ber at spaced points therealong` -(the curls in each fiber length being out of phase with those of an adjacent length) and provide a filter mass of uniform density and possessing an inherent resiliency. The resiliency, as well as a stiffening of the fibers, is provided by the plastic bonding medium. .A filter unit so made needs no external Wrapping or covering for it to ultimately maintain its shape. However, in order to facilitate the placing of --the iilter unit in the lter shell of an air cleaner, it is preferable to bind the unit or otherwise constrict it adjacent'- its ends, so that 4the end portions of the unit will be of less' cross-sectional area than ther intermediate portion. One way of accomplish-- ing this binding, may be by way of a cord or tape; tied around the end portions of the unit in amanner to constrict them somewhat, as indicated at 34-34 in Figure 1. The resultant unit will therefore have what may be considered Somewhat of a barrel shape, and with the reduced end portion, it making no difference which end, the unit may be easily slipped into the lter holding shell I1. By virtue of the fact that the unit was made in a mold'slightly oversize, the body portion of the unit, due to its inherent resiliency, will press against the sides of the shell I1 so that the unit is in effect self-sealing, and it will be appreciated that no gasket means whatever need be associated with the unit to prevent by-passing of air around the unit.

In the event it is ultimately desired to have the filter mass encased in a covering, for example, to replace units in air cleaner casings designed for that type of filter element, it is a simple expedient to pack the plasticized and still damp ber lengths in the particular casing or shell they are to remain in during ultimate use. Such a shell is indicated at 35 in Figure 6 of the drawings, and it may be of sheet metal, or for added economy, of paper board orthe equivalent preferably adequately reproofed.

Still another way of shaping the ultimate filter unit would consist in yseparating or plucking the curled fiber llengths and letting them accumulate in the form of a mat which may be sprayed at various steps with the plastic bonding medium. After the mat has reached a certain height or thickness, the particular lter unit may be out from the mat by means of a device akin to the commonly known cookie cutter, suitable pressure being applied either before or during the cutting operation to compress the mat to the desired extent.

Still another Way of accomplishing this purpose embodies a substitute for the plucking or cardingY operation of the curled fiber lengths. The relativelyshort helical bundles of cut or curled bers maybe placed in the path of an lair blast, which will blast the cut sections into a large chamber and permit the free fibers to settle to the bottom of the chamber. As these fibers are settling to the bottom of the chamber. they may be sprayed with the plastic bonding medium and a uniform bat or mat will accumulate at the bottom of the, chamber, and a cutter akin to a cookie cutter may be utilized to provide the individual lter units. To avoid any waste, the collection chamber may be a mold of the size, or approximately of the size, of the ultimate filter unit and cutting eliminated. v

Itwill of course be understood that other substances, may be utilized for reproong, and other bonding media may also be utilized, the above examples of these particular substances, as well as the above examples of sizes and temperature ranges are given by way of example only and not by way of limitation. Many variations in the above processes will become apparent to those skilled in the art and be well within the purview of this invention.

In Figure 6,k we have illustrated a cleaner adapted for the reception of a filter unit, generallv indicated by numeral 20a, having a coverl ing 35 therearound. In most respects, the cleaner of Figure 6 is of the same construction as that above described inv connection with Figures 1 and 2. The difference resides mainly in the Ainanner of holding the filter unit 29a in the shell l'. In the instance of Figure 6, a supporting bracket 3B secured to the top of the casing carries female stud 3l into which a centrally disposed bolt 38 may be threadedly engaged. This bolt extends entirely through the lter element and has a wing formation 39 on the lower end for manual manipulation. Between the wing 39 and the shell I7 is a spider arrangement 40 which telescopes over the lower margin of the shell and retains the filter element 20a in position.

The cleaner construction is preferably provided with a gasket holding flange 4l which supports a gasket 42 against which the upper edge of the cover 35 of the filter unit abuts.

As stated above, the cover 35 of the filter unit 20a may be of paper board, metal, or any other desirable or suitable substance, and this cover takes the place of the external binding elements 34-34 described in connection with Figure 1. It is not, in fact, by virtue of the plastic bonding of the fibers, essential to provide a covering around the fiber mass, such cover merely functioning as an external binding of the mass, to facilitate its removal and replacement in the lter holding shell IT. The operation of the structure shown in Figure 6 is substantially the same as above described in connection with the structure of Figure 1.

Curled sisal liber filter elements made in accordance with. the instant invention result in several advantages over previously known air clean-` ers. For example, tests have proven that a filter f.

element of the character set forth herein results in increased cleansing efficiency, maintains a low restriction during use, and has a low bulk weight. As a specific example, a curled sisal fiber filter element made up of fibers approximately one inch in length having a one-sixteenth inch curl and a weight of 0.26 gram per cubic inch showed a dust removal efficiency of 98.7% and a pressure increase of only 0.85 inch of water during the test. In comparison, a commercially used air filter employed by the Armed Forces, when tested under identical conditions, showed a dust re-V moval efficiency of 96.4% and a pressure gain across the filter of V2.40 inches of water.

Similar tests have established that a curled sistal fiber filter increases the capacity of the cleaner, in that more cubic feet of air per minute may be passed through the cleaner without danger of the cleansing liquid being carried over into the carburetor with which the cleaner is associated. In addition, the effective weight, that is, the portion of the filter figured on a weight basis which actively participates in removing dust from air traveling therethrough, has proved to be generally higher than that obtained by other filter arrangements.

An outstanding feature of the curled fiber lt-er element is its uniformity and the ease with which that uniformity may be reproduced from filter to lter during commercial manufacture. Under commercial operating conditions, the dust removal efficiency of the curled fiber filter unit should be controllable without any excess effort in that regard within less than one-half of one percent. The factor to which this reproducible uniformity characteristic is attributed is that a curled fiber lter element has fibers running parallel to the ow of air, transverse thereto -and obliquely thereto. VThe relative proportion of each curled fiber which will be disposed parallel to the air flow as compared with that portion of the fiber which will be disposed in a direction transverse tothe air flow will be altered very little regardless of the position of the curled fibers in the filter mass. Because of the uniformly curled shape of the fibers, there is no possibility of the fibers lying on their sides or compacting. Likewise, there is substantially no possibility of the completed filter mass becoming channeled. The inherent resiliency of the filter unit tends to resist such channeling in addition to other factors.

It will, of course, be understood that various details of the process and construction may be varied through a wide range without departing from the principles of this invention and it is, therefore, not the purpose to limit the patent granted hereon other-wise than necessitated by the scope of the appended claims.

We claim as our invention:

1. A filter unit for liquid bath automotive air cleaners, said unit being 'made up of a mass of vegetable fibers initially loosely bunched and curled in strands, said curled strands being cut in relatively short lengths and being bonded together at random by a dry setting plastic sub stance, said filter unit being of uniform density and inherent resiliency.

2. A filter unit for an air cleaner, including a mass of sisal fibers initially loosely bunched and curled in strands, said curled strands being cut in lengths not exceeding two inches and having a plurality of curls to each length, said lengths being bonded together at random by a dry setting plastic substance to provide a homogeneousv filter mass of uniform density.

3. A dry filter unit, including a mass of vegetable fibers initially loosely bunched in strands, said strands being treated with a flame-proofing agent and subsequently curled and set by the action of said agent, said strands being further cut into short lengths with a plurality of curls to each length, said lengths being bonded together at random by a dryl setting plastic material, thereby imparting resiliency and uniform density to said filter unit.

JOSEPH B. SEBOK. W'ILLIAM H. BROWNE. ARNOLD E. PAVLISH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,375,498 Farmer Apr. 19, 1921 1,829,401 Kamrath Oct. 27, 1931 1,829,618 Studer Oct. 27, 1931 2,019,241 Weiss Oct. 29, 1935 2,062,090 Gaarder et al Nov. 24, 1936 2,112,799 Williams Mar. 29, 1938 2,152,901 Simison Apr. 4, 1939 2,167,323 Hegan July 25, 1939 2,178,614 Slayter Nov. 7, 1939 2,189,840 Manning Feb. 13, 1940 2,196,469 Moeller Apr. 19, 1940 2,416,851 Sebok Mar. 4, 1947 2,492,083 Zelinski Dec. 20, 1949 FOREIGN PATENTS Number Country Date 541,441 Great Britain Nov. 2'6, 1941 112,138 Australia Dec. 11, 1940 492,235 France Mar. 11, 1919 766,983 France July 7, 1934 

